Hermetic endoscope assemblage

ABSTRACT

Hermetically sealed enclosures and constructions are disclosed for use in endoscopic systems, particularly endoscope systems with electronic imaging and illumination systems in the enclosures. Compound optical windows are also disclosed for use in the systems. The compound optical windows may have separate panes for an imaging system and an illumination system, and contrast-reducing optical boundaries are between panes.

BACKGROUND

A medical endoscope is an instrument used to inspect the inside of abody. A typical endoscope has a distal end comprising an optical orelectronic imaging system, a proximal end with control for manipulatingthe tool and devices far viewing the image, and a solid or tubularelongate shaft connecting the ends. To use an endoscope, a physicianinserts the distal end into a patient through a natural orifice or anartificial incision and than pushes the shaft into the patient until thedistal end reaches a site of interest. The proximal end remains outsidethe patient and typically connects to an eyepiece, video monitor, orother equipment. Some endoscopes let the physician pass tools ortreatments down a hollow channel, for example, to resect tissue orretrieve objects. Other endoscopes are strictly inspection devices andnot used for remote procedures.

After an endoscope is used on a particular patient, the endoscope mustbe sterilized before it can be used again. The goal of sterilization isto remove all foreign matter and all pathogens. A traditional method forsterilizing metallic surgical instruments is to place them in a devicecalled an autoclave. An autoclave is a strong, enclosed pressure vesselwith a heater and a pressure-tight door. An autoclave heats its contentswith pressurized steam to a high temperature, above the boiling point ofwater, killing pathogens and microorganisms.

The high temperature and pressure within an autoclave can damage ordegrade endoscopes and similar instruments, however. As endoscopes havebecome more sophisticated and costly, it has become more important toreduce or prevent this damage and degradation while continuing to relyon an autoclave for positive sterilization.

A typical electronic endoscope may contain circuit boards, integratedcircuits, conductors, connectors, lenses, prisms, image sensors, and soon. A typical endoscope protects these internal parts, for example,during sterilization, through a sealing system based on O-rings,silicone seals, epoxy seals, or similar flexible, semi-flexible, oradhesive sealants. Unfortunately, some of these sealing methods cannotwithstand repeated exposure to pressurized steam in an autoclave or toother sterilization conditions. Sterilization procedures for endoscopescommonly start with partial or total disassembly followed bysterilization by immersion in sterilant gasses, liquids, or plasmas.These sterilization procedures are labor-intensive and expensive. Worse,they are not always totally effective at disinfecting anddecontaminating the instrument. Disease-causing microorganisms maysurvive processing, creating a risk of iatrogenic infection tosubsequent patients—a complication that contributes to extended hospitalstays and increased mortality and morbidity.

What is needed is an electronic endoscope that can withstand rigoroussterilization in an autoclave—which, by necessity and design, creates avery harsh environment. Ideally, the endoscope would not requiresignificant disassembly prior to autoclaving. Ideally, it would surviverepeated autoclaving without damage or degradation. Some attempts havebeen made to provide hermetic enclosures. For example, U.S. Pat. No.6,572,537 discloses an endoscope having a solid-state image pickupdevice with a distal tip sapphire window and a sapphire rear end cover.The cover and window are subjected to a metallization process and thenjoined by an airtight brazing process to metal members to form ahermetic seal. Soldered or brazed connections are used in various otherplaces in the device to form hermetic seals. (See also U.S. Pat. Nos.6,716,161; 6,547,722; 6,547,721; 6,425,857; 6,328,691; 6,146,325;6,080,101; 6,030,339; 5,868,664; 5,810,713; 5,188,094; and 4,878,495).All the foregoing patents are hereby incorporated by reference, as ifset forth herein in their entireties.

Unfortunately, the foregoing needs have not been met by the prior artbecause the mere design of a hermetic enclosure, which might be capableof withstanding harsh environmental conditions, does not automaticallysatisfy other functional and operational needs. In particular, differentparts of an endoscope ideally require different material attributes.Some desirable materials that can withstand harsh conditions may noteasily join to other desirable materials. This is certainly the caserelative to, for example, aluminum, stainless steel, and titaniummetals, or their alloys, each of which may provide desirable operationalor functional attributes. More specifically, the need to join dissimilarmetals partly result from the part-by-part selection of materials guidedby the purpose of each part and the properties of the available metalsand alloys. The parts of medical instruments that actually enter apatients body are often made from stainless steel, an FDA-approvedmaterial with corrosion-resistant properties desirable for maintaining asterile surface. Stainless steel has poor heat conductivity and isrelatively heavy, however. Aluminum, in contrast, has excellent heatconductivity, making it a preferred material for the parts of medicalinstruments that contain heat sources such as electrical or electronicdevices. Aluminum is also lighter than stainless steel making it hatterfor large parts, especially those require that precise manipulation.Aluminum is unfortunately prone to oxidation, making it non-ideal forparts that pass into the body; and aluminum is relatively soft, makingit non-ideal for parts exposed to friction, scratching, and wear.Titanium, on the other hand, is exceptionally strong, hard, and tough,making if preferential for parts exposed to friction and wear. As aresult of its toughness, titanium traditionally has been difficult tomachine, so that titanium parts have bean expansive. Ongoingimprovements in metalworking technologies have lead to an ongoingexpansion or the use of titanium in medical instruments and elsewhere.

Producing a hermetic enclosure greatly benefits from the ability to formfused joints such as welds. Dissimilar metals such as stainless steel,aluminum, and titanium are difficult or impossible to weld to each othervia laser welding, arc welding, and similar techniques, however. Oneapproach would be to manufacture all structural components fromcompatible metals or alloys. For example, the structural parts of theobjective head, shaft, and handle all might be made from stainlesssteel, facilitating the formation of fused joints. This approachprecludes the part-by-part selection of metals and alloys, aconsiderable drawback. Fusing optical glasses used in objective headspresents similar challenges.

SUMMARY OF THE INVENTIVE CONCEPTS

In certain embodiments, the present inventive concept is directed to ahermetically sealed endoscope, as well as related methods, with thefollowing qualities, alone or in combination:

In certain embodiments, the present inventive concepts are directed to ahermetically sealed enclosure, suitable for use in an electronicendoscope, with an onboard image sensor such as a CCD or CMOS chip,capable of repeated sterilization cycles in an autoclave. To surviverepeated autoclaving without motor disassembly, an endoscope enclosureprotects all joints, controls, and connections with melted-metal orcoalesced-metal sealing techniques, such as soldering, bracing, laserwelding, or friction welding, it may also use melted glass plugs throughwhich electrical leads may pass from the interior of an enclosure to theexterior. It does not need to employ exposed O-ring seals, siliconeseals, epoxy seals, or similar flexible, semi-flexible, or adhesiveseals.

Certain embodiments of the present inventive concept protect allinternal parts of the imaging system, including the optical system, theillumination system, or both by using ports or windows made fromnonmetallic, optical materials, such as, optical sapphire, that aresoldered into an aperture provided in a cap-like cover that issubsequently welded to the endoscope shaft. The assembly by melted-metalseals creates a hermetically sealed objective head that protects theoptical and illumination systems. Pre-soldering the windows and portsinto the cover, and subsequently welding the cover to the shaft,advantageously eliminates heat damage during assembly to both opticaland illumination components. Illumination components such as fiber-opticbundles and LEDs are particularly heat sensitive, an attribute thatmight otherwise force the use of an epoxy seal (for example) between thelight port and cover. Pre-soldering the light port into the covereliminates this non-durable, non-hermetic seal, so that not only theoptical system out also the illumination system gains the benefit ofhermetic closure. In other embodiments, the present inventive conceptscontemplate single or compound optical windows affixed by an opaquejoint, formed by soldering with gold, its alloys, or similar metals oralloys. A benefit of an opaque joint is to reduce reflections within orbetween optical elements, increasing contrast and improving imagequality.

In other embodiments, the present inventive concepts achieve improvedcontrast through the use of one or more grooves inscribed into one ormore surfaces of an optical element to subdivide it into variousregions.

In still other embodiments, the present inventive concepts contemplate ahermetically sealed housing portion formed of dissimilar metals, such asstainless steel, titanium, aluminum, and nitinol. The housing portionmay be permanently affixed to the shaft of an endoscope or releasablyattached thereto. In certain embodiments, the housing portions containan imaging system.

In still other embodiments, the present inventive concepts contemplate ahandle portion that employs Hall-effect or other electromagneticswitches for controls, eliminating the perforation of the endoscopehandle and preserving its hermetic closure.

These and other inventive embodiments are described in more detail inthe following detailed descriptions and the figures.

BRIEF DESCRIPTION Of THE DRAWINGS

FIGS. 1 through 16C show representative embodiments according to theprinciples the present inventive concepts, wherein the same or similarfeatures share common reference numerals in a range of 1-99, which inthe case of a similar or analogous feature may be preceded by a numeralin the hundreds range. For clarity, each reference numeral may refer toan item considered generally and abstractly, as well as to instances ofthe item in the context of one or more embodiments.

FIG. 1A shows a side view of a representative endoscopic systemaccording to the present inventive concepts;

FIG. 1B shows a top view thereof;

FIG. 1C shows a proximal-end view thereof;

FIG. 2A shows a distal-end view of a distal tip of an objective headwith a plurality of panes, according to the present inventive concepts;

FIG. 2B shows a longitudinal section thereof, taken along line 2B-2B inFIG. 2A;

FIG. 2C shows a cross-section thereof, with some components removed,taken along Line 2C-2C in FIG. 2B;

FIG. 2D shows a distal-end view thereof, with a differentcross-sectional line 2E-2E;

FIG. 2E shows another longitudinal section thereof, taken along line2E-2E in FIG. 2D;

FIGS. 3A and 3B show a side view and corner detail of an exemplary panefor use in an endoscopic system, according to the present inventiveconcepts;

FIG. 4A shows a distal-end view of the distal tip of an alternativeembodiment of an annular (ring-shaped) pane;

FIG. 4B shows a longitudinal section thereof, taken along line 3B-3B inFIG. 4A;

FIG. 4C shows an and view of the light port in isolation;

FIG. 4D is a side view thereof;

FIG. 5A shows an end-view of the distal tip of an alternative embodimentadapted to acquire an image an angle with respect to the longitudinalaxis;

FIG. 5B shows a longitudinal section thereof, taken along line 5B-5B inFIG. 5A;

FIG. 6A shows a front view of an alternative embodiment of an opticalwindow or a light port with a half-moon-shaped exposed face;

FIG. 6B is a bottom thereof,

FIG. 6C is a side view thereof,

FIG. 7A shows a front view of a compound window assembly comprising twoof the windows of FIG. 6A, gold soldered together;

FIG. 7B is a cross-section thereof, taken alone line 7B-7B in FIG. 7A;

FIG. 8A shows a front view of an alternative embodiment of a compoundwindow assembly comprising two of the windows of FIG. 6A withintermediate fused glass frit;

FIG. 8A shows a cross-section thereof, taken along line 8B-8B in FIG.8A;

FIG. 9A shows a front view of another alternative embodiment of acompound window structure;

FIG. 9B shows a cross-section thereof, taken along line 8B-8B in FIG.9A;

FIG. 10A shows a side view an alternative embodiment of an opticalwindow with grooves that divide the window into optical regions;

FIG. 10B shows a cross-section thereof, taken along line 10B-10B in FIG.10A;

FIG. 11A is a longitudinal cutaway view of the proximal handle portionfor use in an endoscopic system, such as that of FIG. 1A, according tothe present invention;

FIGS. 11B, 11C, and 11D are cross-sections thereof, taken along thelines 11B-11B, 11C-11C, and 11D-11D, respectively, FIG. 11A;

FIG. 12 is a longitudinal cutaway view of a blank for the handle of FIG.11A:

FIG. 13A shows a top view of a handle housing formed from the handleblank of FIG. 12;

FIG. 13B shows an end view thereof;

FIG. 13C shows a longitudinal cutaway view thereof, taken along the line13C-13C in FIG. 13B;

FIG. 13D shows another longitudinal cutaway view thereon taken along theline 13D-13D in FIG. 13B;

FIG. 14 shows a cutaway view of a distal transition element for use withthe handle portion of FIG. 13; and

FIG. 15 is a cutaway view of the handle housing assembly of for anendoscopic system such as that of FIG. 1A, according to the presentinventive concepts.

FIG. 16A shows a side view of an alternative embodiment of a housingportion according to the present inventive concepts.

FIG. 16B shows a front view of the housing portion of FIG. 1A.

FIG. 16C show a rear-view of the housing portion of FIG. 1C.

The foregoing is not intended to be an exhaustive list of embodimentsand features of the present inventive concepts; persons skilled in theart are capable of appreciating other embodiments and features from thefollowing detailed description in conjunction with the drawings.

DETAILED DESCRIPTION OF THE INVENTIVE CONCEPTS Definitions

“Hermetic” and its variations herein refer to a sealed, gas-tight, andfluid-tight vessel, tuba, or enclosure relative to the environmentalconditions under which a housing or enclosure relative to theenvironmental conditions under which an endoscopic housing or enclosuredescribed herein would normally be subjected.

“Melted-metal seal” and its variations herein refer to any joint formedby any of various soldering, brazing, welding, or fusion techniques suchas laser welding, and gold soldering.

“Dissimilar metallic materials” in the context of this applicationrefers to metallic materials that are not directly joinable by weldingtechniques for forming melted-metal seals, due to melting point ormetallurgical incompatibilities in the base metal materials to bejoined.

“Gold soldering” herein refers to the use of gold or its alloys as afusible material to form a joint between base materials. All jointsidentified as gold soldered indicate that gold or gold-based solder orfiller is a preferred welding technique for medical endoscopic systems,because it creates a biocompatible, ductile, chemically inert hermeticclosure at a relatively low temperature. It is understood that “goldsoldering” herein does not exclude the use of other fusible materials,metals, or alloys, particularly if the fusible material is biocompatibleand can withstand repeated autoclave cycles. Soldering with otherbiocompatible metals or alloys, for example, may replace gold solderingfor certain joints.

“Laser welding” herein refers to any of various welding techniques thatemploy substantially coherent light to generate the heat required tofuse parts together. All joints identified as laser welds indicate thatlaser welding is a preferred technique because it is clean, accurate,fast, and does not damage sensitive components, it is understood that“laser welding” herein does not necessarily exclude alternative joiningtechniques such as gold soldering, electronic beam welding, and pressfit, however.

“Light” includes both visible and invisible portions of theelectromagnetic spectrum, as well as polarized, pulsed, filtered, andcoherent (laser) light.

“Pane” or “optical pane” as used herein refers to windows or ports withany transmissive efficiency that allow transmission of some portion ofthe electromagnetic spectrum for purposes of image acquisition by animaging system for an endoscope or for illumination of a target site ina patient's body.

“Prism” herein includes a mirror or other optical element for divertingthe path of a light ray.

Referring to FIGS. 1A, 1B, and 1C, endoscope 20 comprises a distal endportion 22 including an objective head 28, a shaft 26, and a proximalend portion 24 including a handle portion 50. Referring to FIGS. 2A-2E,objective head 28 includes an electronic imaging system 30 for acquiringan image and an illumination system 32. Imaging system 30 typicallyincludes an optical system 31, and one or more image-capture devices 38,plus supporting electronics, conductors, and connections. As discussedin more detail below optical panes of light transmissive material have asurface on the exterior of the endoscope and are in optical alignmentwith the imaging system and illumination system. (A “pane” may also bereferred to herein as a “window” or “port”, or portion of either,depending on function.)

Optical system 31 typically includes one or more panes comprising anoptical windows 34 and one or more internal optical elements 33 athrough 33 n. Internal elements 33 a through 33 n may include lenses,prisms, or mirrors, alone or in any combination. Some embodimentsfurther include a prism 36 adapted to reflect light to image-capturedevice 38.

Optical window 34 is a port, capable of allowing transmission ofelectromagnetic energy such as visible light. The port is disposed inthe distal tip of objective head 28 to seal or protect imaging system 30and, optionally, to provide optical effects. Window 34 may be opticallycoated (for example, to improve light transmission) or colored orpatterned (for example, to filter or otherwise modify light enteringoptical system 31). Window 34 may be a circular cylinder, mounted in thedistal tip of objective head 28 with its axis parallel to objective axis25, exposing a circular face, as shown in FIGS. 2D and 3F. But, anyshape that covers the objective element of imaging system 30 is suitablefor the purpose. For example, the exposed face may be square,rectangular, linear, polygonal, or irregular.

In certain embodiments, objective head 20 includes a windowed closurefor the distal end of shaft 26, such as cap-like, metal cover 40 joinedto shaft 26 at weld 42 as discussed below. The distal surface of cover40 provides an aperture or other receiver for holding each opticalwindow 34, each light port 35, or compound window assembly, as detailedbelow. In an embodiment, the outer diameter of cover 40 substantiallyequals that of shaft 26, so that cover 40 abuts shaft 26 and weld 42 isa butt joint in another embodiment cover 40 slips over the distal end ofshaft 26. Accordingly, the inner diameter of cover 40 approximatelyequals the outer diameter of shaft 26, so that cover 40 overlaps shaft26, and weld at a position 42 seals the proximal end of cover 40 againstthe adjacent inserted surface of shaft 26. In another embodiment, cover40 slips into the distal end of shaft 26. Accordingly, the outerdiameter of cover 40 approximately equals the inner diameter of shaft26, and weld 42 seals the distal end of shaft 26 against the adjacentinserted surface of cover 40. The phrases “inner diameter” and “outerdiameter” herein refer to the nesting sequence of cover 40 and shaft 26and do not imply that cover 40 and shaft 26 necessarily have a circularcross-sectional profile. The outer profile of the inserted part shouldgenerally conform to the inner profile of the surrounding part,facilitating the formation of a hermetic seal at weld 42.

Illumination system 32 is a means of illuminating the site of interest,typically with visible light, but alternatively with any part of theelectromagnetic spectrum. Illumination system 32 includes at least onelight source 65 (FIGS. 11 and 15), at least one pane comprising lightport 35, and, in some embodiments, at least one light conductor 67.Light source 65 may be, for example, one or more solid-state lightingsources (e.g., LEDs), which may be located anywhere inside endoscope 20.Alternatively, light source 65 may be a light conductor such as afiber-optic bundle coupled to an external light source. Otherlight-generating devices are within the scope of the present inventiveconcepts.

Illumination system 32 may rely on one or more light conductors 67 suchas one or more fiber-optic bundles to transmit light from light source65 to light port 35 and subsequently to the site of interest. Forexample, as shown in FIG. 15, light source 65, here one or more LEDs inhandle 50, generates light transmitted by light conductor 67 throughshaft 26 to objective head 28. In an alternative embodiment, one or morelight sources 67 may reside within a housing or enclosure, such as theobjective head 28 portion of the endoscope shaft, eliminating one ormore light conductors 67.

Light port 35 is a pane similar to optical window 34 and set into cover40 at the distal tip Of endoscope 20 to protect at least oneillumination system 32 having at least a light source, to alter thecharacteristics of the transmitted light, or both. Light port 35 may betransparent, translucent, optically coated, or colored to form a filteror to achieve other desired optical effects. For example, light port 35may have a frosted surface to diffuse light from illumination system 32.Light port 35 may be a circular cylinder as shown in FIGS. 2D and 3F,mounted to expose a circular face. Any shape that creates a cover for atleast one illumination system 32 is suitable for the purpose, however.For example, the exposed face may be square, rectangular, linear,polygonal, or irregular. For example, FIGS. 4A-D show a light port 135with an annular (ring-shaped or washer-shaped) exposed face adapted tocover multiple illumination systems 32 arranged around the periphery ofthe distil tip of objective head 28, so that “hole” 133 b leaves aninterior portion of the distal tip uncovered. Although light port 135and optical window 32 are often discussed herein as physically distinctparts, some embodiments may employ a single physical part for bothpurposes.

A contemplated material for an optical pane such as window 34, lightport 35, or both, is optical sapphire. Transmissive materials other thansapphire may be suitable for the present inventive concept. In certainembodiments, discussed below, the selected material needs to withstandmelted-metal assembly techniques and the high-pressure, high-temperatureautoclave environment. The choice of optical sapphire reflects itsexceptional hardness and toughness, which reduce the risk of scratchesand other damage during use, autoclaving, handling, and storage. Afilter, coating, or other optical property or treatment may beassociated with a window 34 or port 35 to achieve desired effects.

The arrangement and configuration of optical window 34, light ports 35,and objective axis 25 may be implemented in a variety of ways for thepurposes of the present inventive concepts. FIGS. 4A and 4B show anembodiment with multiple illumination systems 32 arranged around theperimeter of the distal tip of objective head 28. FIGS. 5A and 5B showan embodiment with the objective axis 25 offset at an angle 39 from thelongitudinal axis of objective head 28 via a prism or mirror 37.

Image-capture device (image sensor) 38 may be a Complementary MetalOxide Semiconductor (CMOS) chip, a Charge Coupled Device (CCD) chip, orother device capable of translating an optical image into a digital oranalog signal. Imaging system 30—essentially a miniature videocamera—may be a fixed-focus or focusable system. For additionaldisclosure about imaging systems for endoscopes, see PCT PatentApplication number 03/00399. Publication Number WO 03/098913, titled“Miniature Camera Head” filed 15 May 2003, the entire disclosure ofwhich is hereby incorporated by reference in its entirety.

To help endoscope 20 withstand sterilization conditions, melted-metalseals such as solder joints, brazed joints and other metallic fillers;laser-welded joints; or solid-state coalescence joints (e.g.,friction-welded joints) may be used to create a hermetically sealedenclosure for delicate or sensitive components. Accordingly, endoscope20 may be constructed without any exposed O-ring, silicone, or adhesiveseals such as epoxy seals. Hospital or clinical staff can place theentire instrument—including its handle 50, shaft 26, objective head 28,and imaging system 30—directly into an autoclave. This straightforwardprocedure saves time, saves cost, and reduces the risk of patientcomplications such as iatrogenic infection. The hermetic construction ofan endoscope 20 according to the present inventive concepts helps toprotect and prevent damage or degradation to sensitive system componentsduring autoclave sterilization.

To achieve these benefits, an endoscope 20 according to certaininventive embodiments employs a combination of sealing technologies asdetailed below.

Hermetically Sealing Optical Windows and Light Ports

As discussed above, an electronic endoscope 20 typically includes anelectronic imaging system 30 disposed in an enclosure, such as objectivehead 28, that is insertable into a target site in a patients body. Inthe embodiment shown, the distal-most optical element of imaging system30 is optical window 34, typically a transparent view port mounted onthe distal end of cover 40 to protect the internal components of imagingsystem 30. Each illumination system 32 may have a similar protectivelight port 35.

One embodiment of the present inventive concepts is the hermeticarrangement of imaging system 30 behind optical window 34, andillumination system 32 behind one or more light ports 35, disposed atthe distal end portion of endoscope 20. To achieve a hermetic seal, theattachment method may be a melted-metal seal, such as gold soldering.Similar metals and alloys are within the scope of the present inventiveconcepts, particularly fusible material that is biocompatible and canwithstand repeated autoclave cycles, and can create a soldered or brazedjoint.

For example, FIGS. 2A-3G show various views of an embodiment withoptical panes in the nature of optical window 34 and light ports 35.These panes may be optical sapphire. In the embodiment shown, eachwindow 34 and port 35 fits into a corresponding receiver at the distalend portion of the endoscope 20. In this example, the receivers areapertures in a cover 40. For medical instruments, a suitable materialfor the receivers is medical grade stainless steel. A fusible material,such as gold solder 44 is applied to the joint or interface between eachwindow 34 or port 35 and its aperture. Gold solder 44 is applied to theentire perimeter of window 34 of port 35 to achieve a hermetic closure.Gold solder 44 may require an application of gold via metallization, tothe perimeter of window 34 or port 35 and to the melting surface of eachaperture in cover 40, to create joint surfaces receptive to gold solder44 or other interface material. Those skilled in the art will appreciatethat equivalent melted-metal sealing techniques may require similartreatments to dissimilar joining surfaces in order to achieve a strongbond. These techniques are well-known in the art. See for example, theprior patents cited in the Background section above.

The assembly sequence of cover 40 and windows 34 or ports 35 is anaspect of the present inventive concepts. During assembly of certainembodiments, each window 34, port 35, or compound window structure issoldered in to its aperture on the distal surface of cover 40 beforecover 40 is welded to the distal end of shaft 26. Creating amelted-metal seal, preferably gold solder, joints 44 on a detached cover40 permits, for example, the subassembly of cover 40, windows 34, andports 35 to cool off before being joined to distal end of shaft 26containing the internal parts of optical system 31 and illuminationsystem 32. Pre-soldering windows 34 and ports 35 into cover 40eliminates heat transfer during the gold soldering process to theinternal parts of optical system 31 and illumination system 32.Pre-soldering therefore eliminates heat damage to the internal parts ofobjective head 28, which may occur at temperatures of about 150° C. Asubsequent laser weld 42 joining cover 40 to shaft 26 does not generateheat that harms optical system 31 or illumination system 32.

A particular benefit to the assembly sequence detailed above is theability to protect both optical system 31 and illumination system 32with melted-metal seals. Illumination components such as fiber-opticbundles and LEDs are especially sensitive to heat damage duringsoldering. Pre-soldering light port 35 to cover 40 specifically permitsthe replacement of a flexible, semi-flexible, or adhesive seal betweenport 35 and cover 40 with a melted-metal seal 44. Totally eliminatingnon-melted-metal seals with respect to optical system 31, illuminationsystem 32, or both, yields an objective head with a durable hermeticenclosure.

Another benefit to the assembly sequence detailed above for an objectivehead is that the cover/panes subassembly may be joined to the shaftassembly in one step, simplifying final assembly and reducing risks tocomponents inside the shaft during assembly. For example, pre-assemblyallows the cover/panes subassembly to be inspected and cleaned beforebeing attached, reducing the risk of trapping flux or other foreignmatter inside the assembled objective head. Soldering windows and portin-place, contrary to the present, inventive concepts, requires amore-complex assembly process with a greater potential for error, lesspotential for intermediate inspection, and closer proximity to delicateparts.

In another embodiment, FIGS. 4A through 4D show an optical window 34with a circular exposed face and a light port 135 with an annular (ring-or washer-shaped) exposed face. In this embodiment, window 34 isattached to cover 40 by gold solder 44 a as described above. Light port135 in contrast, requires gold solder 44 b around the exterior perimeterand gold solder 44 c around the interior perimeter of a hole 135 b.

Compound Window Construction for Improved Optics

Instead of placing panes into separate openings machined into a distalcover, the present inventive concepts contemplate that the imaging andillumination systems may be placed behind a single, common window unit.However, if the systems are not behind separate panes, undesireddiffused or reflected light may enter the imaging system, reducing imagecontrasts or causing other negative light effects. Therefore presentinventive concepts contemplate a single, compound window unit withmultiple panes. The multiple panes may be individual components joinedtogether as a single unit or they may be a monolithic, single unit withdistinct pane zones. Optical boundaries or interfaces formed betweenpanes advantageously reduce internal reflection and light diffusion.Contemplated advantages of the various embodiments of compound windowsinclude reduced cost, ease of assembly, and the ability to select andcustomize each pane 335 according to its particular function andpurpose. For example, FIGS. 6-9 show an optical pane 235 with ahalf-moon shape. Such shapes may be joined to form compound windowstructures.

In another example, FIGS. 7A and 7B show panes 335 joined by, forexample, gold or similar solder 344, which also provides a boundarybetween the panes 335 and around their combined perimeter, forming acompound window assembly. Each of the upper and lower panes may functionas an optical window, light port, or both.

In another example, FIGS. 8A and 8B show panes 435 separated by anopaque boundary substance 444, such as fused glass frit.

In another embodiment, FIGS. 9A and 9B show a compound window assemblywith an optical window 534 set into an aperture cut or formed into lightport 535, with the panes joined by a boundary material 544, such as agold-baaed solder.

The compound windows described herein may be implemented in a range ofsizes and shapes. The compound window shown in FIG. 8A may bedimensioned to provide a minimally invasive endoscope, which would havea diameter slightly larger than that of the window: for example, about a4.5 mm window diameter, with 0.1 mm to 0.2 mm of opaque interface 444.Similarly, the compound window of FIG. 5A may have about a 4.5 mm outerdiameter for the outer pane 535, and the inner pane 534 may have about a2 mm-2.5 mm diameter, with 0.1 mm to 0.2 mm of opaque interface 544.Those skilled in the art will appreciate that various shapes for opticalwindow 34 and light port 35 obligate corresponding adaptations to cover40 and to the application of a boundary material such as gold solder.

The use of gold solder for assembly of panes and formation of a boundaryin a compound window creates a chemically non-reactive hermetic seal forthe compound window. Sapphire and other hard optical materials aredesirable for abrasion and scratch resistance in permanent endoscopesealing windows. These materials are difficult to cut or form. Thismakes forming a compound window of sapphire challenging. Sapphire,however, can be grooved by chemical or ion etching, abrasive cutting, orlaser ablation. With some specific types of glass, such as those usedfor molded lenses, it may be possible to form grooves through aheating-and-coining operation. The grooves alone reduce the reflectedcomponent by dispersing light. The addition of an opaque, absorbingmaterial in the grooves further reduces the reflected component byabsorbing some of the dispersed light.

FIGS. 10A and 10B show a pane 630 with a groove 646 cut, incised,etched, or otherwise indented into its first surface and a second groove648 cut, incised, etched, or otherwise indented into its second,opposing surface. The offsetting of grooves 646 and 648 on oppositesides of the window define pane 635 and produce an effectively deeperand superior optical boundary between a pane for an illumination sourceand a pans for an imaging system. Grooving and opaquing in or on awindow surface reduces or eliminates light piping within the opticalmaterial by introducing light breaks that absorb, disperse, or scatterradiation. This reduces reflective coupling between two parallelsurfaces.

In summary, the present invention contemplates compound panearrangements, where an optical boundary separates panes for an imagingsystem and an illumination system. The optical boundary may be formedfrom opaque material defining a boundary, or indented area of a pane todefine a boundary, or both. Notably, the term “opaque”, as used herein,is a relative term that does not preclude the use of materials that aresubstantially opaque and significantly, but not necessarily completely,reduce an undesired optical effect. A material may also be wholly orsubstantially opaque as to selected portions of the electromagneticspectrum of interest, but not to others that are not of concern.

Melted-Metal Seal Attaching Windowed Closure to Shaft

In the example embodiment shown, endoscope 20 includes a shaft 26 withan imaging system 30 at the distal end portion 22 and a handle portion50 with controls 60. Shaft 26 is essentially a metal tube or pipe,often, but not necessarily, with a circular cross-sectional profile. Inan advantageous assembly method, a distal end portion of shaft 26remains open during assembly, for example, to facilitate the insertionand assembly of imaging system 30. To provide a hermetic closure atdistal end 22, a windowed closure, such as a cap-like cover 40 may beattached to distal and of shaft 26. A swindle cover 40 has anapproximately cylindrical form, closed at its distal end (except forreceivers for optical window 34, light ports 35, or both), and open atits proximal end. The opening at the proximal end el cover 40 should besized and configured to fit the reciprocal open end of shaft 26. Forexample, if the distal end of shaft 26 has a circular cross-sectionalprofile of a given outer diameter, then cover 40 should have a proximalend with substantially the same profile and diameter.

An aspect of the present inventive concepts is the use of at least onemelted-metal or coalesced metal seal at a position 42 on the shaftassembly. Typically, but not necessarily, a laser weld attaches me openproximal end of metal cover 40 to the open distal end of shaft 26,creating a fused, hermetic closure. Laser welding is a preferred joiningtechnique because it is clean, accurate, fast, and does not typicallydamage sensitive components. Alternative joining techniques such as goldsoldering, electron beam welding, and press fit are within the scope ofthe present inventive concepts. For example, FIGS. 2B and 2E showlongitudinal cutaway views of the distal end of a representativeendoscope 20 according to the present inventive concepts. As shown,cover 40 attaches to shaft 26 via a laser weld at a position 42 appliedto the joint between cover 40 and shaft 26. Laser weld 42 is applied tothe entire joining surfaces of cover 40 and shaft 26.

While laser welding generally is known, in this novel application for awindowed closure. It provides a metal seal resistant to pressure,moisture, and heat and therefore able to withstand the harsh environmentwithin an autoclave.

Handle with Enclosed Controls and Hermetic Connectors

The proximal end portion 24 of endoscope 20 includes a proximal noosingportion or handle portion 50 that may contain controls 60, such asbuttons and connection points such as hermetic connector 59. The housingor handle may contain other systems or components, as well. Adaptinghandle 50 to withstand the autoclave environment requires creating ahandle housing 52 that provides for hermetically sealing all connectionsand controls, FIGS. 1A and 1B show an external view of handle 50, andFIGS. 11A and 15 show cutaway views thereof. In the embodiment shown,handle 50 comprises a handle housing 52, a distal transition element 56,a proximal transition elements 57, at least one hermetic connector 59,and zero or mom controls 60. It further comprises zero or more switchmeans that can be activated without creating an opening in a housing,such as handle 52. For example, the switch means may be a Hall-effect orother magnetic, electronic, or wireless switches 62, whichadvantageously do not require any opening in handle housing 52,furthering the objective of creating a hermetic enclosure.

In certain embodiments, the present inventive concepts contemplate theuse of a solid-state welding technique to create a blank 51, formed ofdissimilar materials. A housing 52 so constructed advantageouslypreserves the ability select metals on a part-by-part basis guided bythe purpose of the part and the properties of the available metals andalloys. The large aluminum surface area of handle housing 52, forexample, beneficially improves its ability to dissipate heat. Housing 52simultaneously enables the formation of melted-metal seals yielding ahermetic enclosure.

Handle 40 may include a distal transition element 56. The transitionelement is a transitional cap fabricated from a metal compatible withthat of shaft 26, so that transition element 56 may be joined to shaft26 via melted-metal seal 58 a. For example, if shaft 26 is made from astainless steel, then transition elements is made from a compatiblestainless steel, facilitating attachment of transition element 56 toshaft 26 via a laser weld 58 a. Transition element 56 may be a distinctpart fabricated by, for example, stamping, casting, turning, orspinning; or it may be a transitional shape that is machined into thedistal end of handle blank 51. Transition element 56 is joined to handlehousing 52 via a melted-metal seal. For example, if transition element56 is made from a stainless steel, then distal end of handle housing 52is made from a compatible stainless steel, facilitating attachment oftransition element 56 to housing 52 via laser weld 58 b. FIG. 14 shows across-section of transition element 56 in isolation.

Proximal transition element 57 is a transitional cap made from a metalcompatible with that of hermetic connector 59, so that transitionelement 57 may be joined to connector 59 via melted-metal seal 58 b. Forexample, if the body of hermetic connector 59 is made from titanium,then transition element 57 is also made from titanium, facilitatingattachment of transition element 57 to connector 59 via laser weld 58 b.Transition element 57 may be a distinct part, fabricated by, forexample, stamping, casting, turning, or spinning; or it may be atransitional shape machined into the proximal end of handle blank 51 asshown in PIG. 11. It is noted that a transition element is optional. Forexample, it is contemplated that a shaft may be connected directly to ahousing portion, or the shaft may have a transition element or portion.Hermetic connector 59 is en electrical and electronic connection pointadapted to withstand the high-temperature, high-pressure autoclaveenvironment. Connector 59 provides a means for detachably connectinghandle 50 and thereby endoscope 20 to (for example) a power supply,devices for displaying, processing, or recording the image, and otherexternal equipment via conductors 54. Connector 59 is preferably joinedto handle housing 52 via a melted-metal seal. In an embodiment, the bodyof connector 59 is made from titanium and joined to housing 52 via laserweld 58 c.

A Hall-effect or magnetic switch 62 is a contact-less sensing devicethat operates by sensing either an external magnet or a ferrous object.The electromagnetic operating principle of a Hall-effect switch is knownin the art and beyond the scope of the present disclosure. What isimportant here is that a Hall-effect switch 62, in conjunction with acontrol 60, provides a means for controlling endoscope 20 withoutperforating handle housing 52. Referring to FIG. 15, each Hall-effectswitch 62 resides topologically inside the enclosure of handle 50. Eachcontrol 60 remains topologically outside the enclosure of handle 50. Thecommunication between each Hall-effect switch 62 and the correspondingcontrol 60 is electromagnetic, not mechanical, thereby preserving thehermetic closure of handle 50.

A control 60 is a push button, toggle switch, or similar device affixedto the outside of handle housing 52 and in electromagnetic communicationwith a particular Hall-effect switch 62. Each control 60 comprises amagnet or ferrous object adapted to move in response to a predefineduser action. The corresponding switch 62 detects the motion of themagnet or ferrous object and responds by issuing a control signal to anelectronic component of endoscope 20. The component interprets thesignal in a predefined manner in order to enable, disable, or otherwisemodify a predefined aspect of the operation of endoscope 20.

For example, suppose control 60 is a button configured as a switch toenable or disable an illumination system 32. Depressing control 60 onetime might turn the light source “on,” and depressing control 60 asecond time might turn the tight source “off.” To the user, theoperation of control 60 seems like that of a common toggle switchconnected to illumination system 32. In reality, no mechanicalconnection exists between the button and illumination system 32. Inreality, pressing control 60 one time induces a response in acorresponding Hall-effect switch 62. Conductors within endoscope 20 passthis response, or a derivative of it, to one or more electronic deviceswithin endoscope 20. These devices interpret the response as apredetermined control signal and turn illumination system 32 “on.”Pressing control 60 a second time yields a similar chain of eventsinterpreted as a request to turn illumination system 32 “off.” Thespecific benefit of this adaptation is to provide a mechanism forcontrolling the operation of endoscope 20 without violating the hermeticenclosure of handle 50.

The number of controls 60 (and the corresponding switches 62) depends onthe particular purpose of endoscope 20. A typical endoscope 20 hasseveral controls 60. Embodiments with zero, one, or multiple controls 60are within the scope of the present inventive concepts. An embodimentwith zero handle-mounted controls might provide any needed controlsignals via hermetic connector 62, for example. Alternatively, anendoscopic system may include a remote control that wirelesslycommunicates with systems or components in an endoscope housing,allowing for a hermetic endoscope.

Enclosure of Dissimilar Materials Formed Using Solid-State Welding

Handle 50 is a sealed enclosure that protects switches 62 and otherinternal components of endoscope 20 such as printed circuit board 64,light source 65, and heat sink 66. To facilitate insertion of componentsinto handle 50 during manufacture, handle 50 includes a handle housing52, a distal transition element 56, a proximal transition element 57,and at least one hermetic connector 59. During assembly, thesecomponents are joined by seals (interfaces) 58 a, 58 b, and 58 c to forma hermetically sealed enclosure. Distal transition element 56, proximaltransition element 57, and hermetic connector 59 may be formed fromdissimilar materials. Dissimilar metallic materials may generally bejoined using solid-state welding techniques. Solid-state welding is agroup of techniques that produces coalescence at temperatures below themelting point of the base materials being joined, without the additionof a filler material, it includes, friction welding, cold welding,diffusion welding, explosion welding, forge welding, hot pressurewelding, roll welding, and ultrasonic welding, it is believed that someor all of these techniques may be used to form a hermetic enclosure fora medical instrument, and, in the following description, frictionwelding is used as a representative technique from the group. Generally,friction welding involves pressing base metal materials together andfrictional engaging the materials relative to each other by, forexample, vibration, rotation, or other movement, to generate beet andcoalescence of the materials. Friction welding may also be performed bypressing the materials together and frictionally engaging a tool alongthe boundary of the materials to cause the coalescence. This techniqueis more particularly known as “friction stir welding”.

To facilitate the formation of melted-metal seals, handle housing 52 maybe a friction-welded structure as described below.

FIGS. 12 and 13A-13D show one possible construction of handle housing52. In this embodiment, housing 52 is machined from a friction-weldedblank 51, Blank 51 comprises an intermediate section or core 74, adistal cap 72, and a proximal section, such as cap 76. Cora 74 may beformed from a metal, such as aluminum, selected for its light weight andheat dissipation. Distal cap 72 may be formed from a metal, such asstainless steel, selected for compatibility with distal transitionelement 56. Proximal section 76 may be formed from a metal selected forcompatibility with hermetic connector 59. Core 74, distal cap 72, endproximal cap 76 may be dissimilar materials not readily joined byconventional melted-metal seal welding, for example. To overcome thisdissimilarity, blank 51 may be fabricated by friction welds at positions78 a and 73 b. Blank 51 therefore is a kind of laminated structure, withdistal cap 72 clad to the distal end of blank 51 at friction weldposition 78 a, add proximal cap 76 clad to the proximal end of blank 51at friction weld position 78 b. Friction-welding techniques known in theart may be used in this novel construction of an endoscope handle. Blank51 may subsequently undergo machine operations known in the art toproduce the specified form of handle housing 52.

For example, assume that distal transition element 56 is stainless steeland the body of hermetic connector 59 is titanium. Further assume thatcore 74 is aluminum. In this case, distal cap 72 is joined to the distalend of aluminum core 74 at friction weld 78 a, and proximal cap 76 isjoined to the proximal end of aluminum core 74 at friction weld 78 b. Ahandle housing 52 derived from this blank 51 is thereby configured tofacilitate the formation of melted-metal seals 58 b and 58 c, such aslaser welds. After inserting components into handle housing 51, sealssuch as laser welds 58 b and 58 c yield a hermetically sealed enclosurethat can withstand autoclave sterilization.

Summarizing, to create a hermetically sealed endoscope 20, all jointsfrom the distal tip 22 to proximal end 24 are formed by melted-metal orcoalesced metal seals such as soldering, laser welding, and frictionwelding. For example, in the embodiment of FIG. 1, the joint sequence,distal to proximal, starts with sapphire optical window 34 and sapphirelight ports 35 gold soldered at 44 to apertures so the distal tip of astainless stool cover 40. Cover 40 is laser-welded at 42 tostainless-steel shaft 26, which is laser-welded at 58 a to the distal(apical) end of a stainless-steel distal transition element 56. Theproximal (basal) end of distal transition element 56 is laser welded at58 b to stainless-steel cap 72 at the distal end of handle housing 52.Cap 72 joins to aluminum core 74 via friction weld 76 a. Core 72 joinsto a titanium proximal cap 76 via a friction weld at 78 b. Cap 76 isjoined to hermetic connector 59 at laser weld 58 c. Accordingly, theentire endoscope 20 may be placed in an autoclave for sterilization.

As to controls, the present inventive concepts contemplate the use ofone or more Hall-effect or other magnetic switches 62 inside the sealedhandle housing 52. Such switches 62 operate by sensing either anexternal magnet or a ferrous object, contained in, for example, acontrol button 60 applied to the outside of a sealed handle 50. The useof a control button 60 that relies on a magnet or ferrous object tocommunicate with a Hall-effect switch 62 creates for handle-mountedcontrol that does not breach the hermetically sealed handle housing 52.FIGS. 16A-C, show an alternative embodiment of a housing portion 150 foran endoscopic System. In this system, the housing portion encloses acamera assembly that includes an imaging system (not shown). The imagingsystem may include one or more image sensors. The housing portionincludes a mechanical coupling system 790 for releasably coupling thehousing portion to an endoscope, typically at the proximal end of theendoscope, at an aye piece. Coupling systems for proximal,camera-endoscope assemblies are well-known in the art and are notdetailed here. In one possible embodiment, the imaging system is a3-chip system. Each chip is dedicated to a specific band of light,typically primary color. The housing includes optical elements for theimaging system, such as a band separator for separating light intobands, such as the primary colors. An example band separator is a prism,and it is arranged in the housing to deliver each band of light to thechip dedicated to a particular band. The housing portion may alsoinclude a set 780 of hermetic connectors, as described above for otherembodiments.

The housing portion includes a proximal window 735 that is arranged tooptically align with the optical train or elements of a scope and alsowith the imaging system in the camera housing. The window is set in afront closure 740 for the camera housing, which may include one or moresections. The closure 740 has a receiver for window 735, similar to thearrangement discussed above for a window at the distal end of anendoscope shaft. The window may be sapphire, and the receiver may bedefined by a metal fitting or insert 741 included as part of theclosure. The window is preferably joined to a metal closure by amelted-metal seal, such as gold soldering 742.

The insert 741 may be joined to a second section 743 in the closure ofthe same or dissimilar metal as the resort. For example, the secondsection may be formed of aluminum. The closure 740 may be joined to abody section 745 made or aluminum or other metals by melted metal seals(e.g., laser welding or solid-state-welding (e.g., friction welding).Housing portion 150 may also have a rear portion 770 with a connector771 for electrical coupling with other systems such as video processingand power. This rear connector is generally similar to that in theendoscope embodiments described above. To hermetically seal the housing,the rear portion includes a glass plug 772 formed from molten sapphire,for example. Conductive pins (not shown) hermetically extend from theinterior of the housing, through the plug, to the exterior of thehousing. The glass plug is formed in a metal insert or fitting 772,which may be fitted in or formed with a flange 773. These parts, ifseparate pieces, may be stainless steel and laser welded together. Thestainless steel insert in turn is set in another section of the housing776, which may be a dissimilar metal, such as aluminum. As with otherembodiments, a solid-state welding technique, such as friction, may beused to join dissimilar materials. The foregoing housing assemblyadvantageously uses melted materials and melted or coalesced metal sealsto provide a hermetically sealed housing for a releasable camera thatmay be used with new endoscopes or an existing base of conventionalendoscopes.

Further details for the construction of a hermetic, releasably-culpablecamera assembly are disclosed in co-pending U.S. application Ser. No.11/109,902, filed Apr. 19, 2005 (provisional 60/563,357 filed Apr. 10,2004), Attorney Docket No. ACME-2.068.US, entitled AUTOCLAVABLE VIDEOCAMERA FOR AN ENDOSCOPE, which is assigned to the assignee of theinventive concepts described herein. The '902 application also discloseshermetic switches, controls, and lens assemblies for a hermeticenclosure. The '902 application is hereby incorporated by reference asif set forth herein in its entirety.

Some or all the present inventive concepts generally may be employed inany kind of endoscope for any kind of medical or industrial application,including rigid endoscopes, capsule endoscopes (e.g., free moving in thegastrointestinal tract), and flexible endoscopes. In addition totraditional constructions of flexible endoscopes, a novel flexible shaft26 may be fabricated from a super-elastic metal, such as Nitinol orMP35N, configured in spaced flexural lines wholly or partiallycircumscribing the shaft, similar to accordion-pleats. The operatingprinciple is equivalent to that of the familiar flexible soda straw.Advantageously, a flexible shaft formed from a unibody of metal providesa seamless a hermetic enclosure.

Persons skilled in the art will recognize that many modifications andvariations are possible in the details, materials, and arrangements ofthe parts and actions which have been described and illustrated in orderto explain the nature of the inventive concepts and that suchmodifications and variations do not depart from the spirit and scope ofthe teachings and claims contained therein.

1-17. (canceled)
 18. A windowed closure comprising: a metal material andhaving a first receiver including a plurality of panes arranged as acompound window, at least one first pane aligning optically with animaging system and at least one second pane aligning optically with anillumination system; an optical boundary provided between adjacent edgesof the at least one first pane and the at least one second pane toreduce transmission of light across the optical boundary between thepanes; wherein the plurality of panes are disposed in the receiver andjoined to it by a melted-metal seal, the closure being adapted toconnect to an endoscope shaft. 19-25. (canceled)
 26. The closure ofclaim 18 wherein the optical boundary comprises an indented area in thewindow. 27-57. (canceled)
 58. The closure of claim 26, wherein theoptical boundary includes a first groove formed in a first surface ofone or more of the plurality of panes.
 59. The closure of claim 58,wherein the optical boundary includes a second groove formed in a secondsurface of one or more of the plurality of panes.
 60. The closure ofclaim 59, wherein the first surface opposes the second surface.
 61. Theclosure of claim 59, wherein the first and second grooves are offsetfrom one another.
 62. The closure of claim 59, wherein one or more ofthe first and second grooves are formed by etching.
 63. The closure ofclaim 18, wherein the optical boundary is formed with an opaquematerial.
 64. The closure of claim 18, wherein the optical boundary isformed with an indented area.
 65. The closure of claim 59, wherein thefirst and second grooves are rounded in shape.
 66. The closure of claim59, wherein the first and second grooves are substantially rectangularin shape.
 67. A windowed closure comprising: a metal material and havinga first receiver including a plurality of panes arranged as a compoundwindow, at least one first pane aligning optically with an imagingsystem and at least one second pane aligning optically with anillumination system; an optical boundary formed as one or more indentedareas provided between adjacent edges of the at least one first pane andthe at least one second pane to reduce transmission of light across theoptical boundary between the panes; wherein the plurality of panes aredisposed in the receiver and joined to it by a melted-metal seal, theclosure being adapted to connect to an endoscope shaft.
 68. The closureof claim 67, wherein the one or more indented areas include a firstgroove formed on a first surface of the plurality of panes and a secondgroove formed on the second surface of the plurality of panes.
 69. Theclosure of claim 66, wherein the first groove and second groove areoffset from one another.
 70. The closure of claim 68, wherein one ormore of the first grove and second groove are formed at an angle so thatreflection across the optical boundary is reduced.
 71. The closure ofclaim 67, wherein the indented area is formed by etching to preventreflections across the optical boundary.
 72. The closure of claim 67,wherein the indented area is provided with frosting to preventreflections across the optical boundary.
 73. The closure of claim 68,wherein one or more of the grooves are formed by etching to preventreflections across the optical boundary.
 74. The closure of claim 68,wherein one or more of the grooves are provided with frosting to preventreflections across the optical boundary.
 75. The closure of claim 67,wherein the one or more indented areas include a first groove formed ona first surface of the plurality of panes.
 76. The closure of claim 67,wherein the plurality of panes are formed in concentric circles.
 77. Theclosure of claim 67, wherein the plurality of panes are formed in nestedcircular arcs.